TypHa Insects: THerrR EcotocicaL RELATIONSHIPS 491 
flowers, and later from the seeds and the dried-up parts of the flower. 
As soon as hatched, the larva begins to feed on the styles, leaving the 
{stigmas to form a sort of covering over itself. These severed stigmas are 
spun together with a little silk and thus held in place. The larval habits 
fof both Lymnaecia phragmitella and D. julianalis are very similar in their 
early stages. As the cat-tail heads become more mature; and the larvae 
grow larger, they enter deeper into the head, and their presence is not 
{so readily detected as when they are working near the outer surface where 
the little raised patches of fluffy material they produce are easily seen. 
|The appearance of a head of Typha within a week after the larvae had 
hatched and entered the head is shown in Plate XLIX,86. As inthe case 
of Lymnaeciaphragmitella, the seeds are kept from scattering, by being tied 
together with silk woven by the larva. Neither wind nor rain is able to 
{tear apart the heads so protected. Accordingly they form a good shelter for 
the larvae during the winter. The larvae of D. julianalis bore into the 
jaxis of the flower spike and there spend the winter in the half or two-thirds- 
grown stage. The rachis, with the characteristic tunneling of the larvae, 
jis shown in Plate XLIII, 42 and 43. These tunnels are later lined with a 
jlittle silk and in themthelarvae construct tightly-woven cocoons in which 
they transform to the pupal stage. Many of the larvae, however, remain 
in the fluffy material in the heads to spin their cocoons and pupate. 
Pupation begins about the first of June. The adults emerge during the 
latter part of June and the first part of July. 
} During the spring of 1916 the author did not find any dead larvae in 
the heads of the cat-tail; but in the spring of 1918 all the larvae of this 
|species which he observed were dead, evidently having been killed by 
\the severe cold of that winter. At that time even the larvae in tunnels 
of the axes of the heads were dead. ‘This was not true of the larvae of 
|Lymnaecia phragmitella, however: 
Description of the stages 
The egg 
Elongate oval, tapering considerably toward the posterior end and rather blunt at the 
| anterior end (Plate XLIII, 38). Very long in proportion to its width, measuring 1 mm. in 
length and 0.219 mm. at its greatest diameter. Color of egg white, with a slight bluish 
| tinge in refracted light. Sculpturing rather-faint, consisting of fine, more or less hexagonal 
reticulations (Plate XLIII, 39, drawn with the camera lucida). 
) 
} 
